Using Inertial Sensors to Improve GPS Performance

GPS works best with a good view of the sky. When the sky view gets obstructed, for example in an aircraft roll or when a smartphone gets taken indoors, GPS will not continue to track and the navigation capability is lost. Inertial sensors continue working in all conditions – move them and you get an output from the sensor. The biggest weakness of inertial sensors is that errors are cumulative.

By combining GPS and inertial, the GPS can provide the reference positions and inertial can provide continuity at all times. The basic principles are similar whether in a military jet or a smartphone.

Military grade systems generally use dual-frequency GPS for better accuracy and resilience. The inertial systems in military systems are high grade, often with inertial drift of only a few degrees per hour. This enables the inertial sensors to be used for navigation with GPS providing re-calibration periodically.

MEMS sensors and GPS are increasingly common now in smartphones and consumer grade navigation systems such as PNDs. However, the sensors used are very low cost and accuracy can be poor even over short distances or time periods.